Problem: Simplify. Rewrite the expression in the form $b^n$. $\dfrac{b^{-2}}{b^{4}}=$
Answer: Recall that $\dfrac{x^n}{x^m}=x^{n-m}$. $\begin{aligned} \dfrac{b^{-2}}{b^{4}} &= b^{-2-4} \\\\ &= b^{-6} \end{aligned}$